1. Field of the Invention
This invention relates to a primary cable apparatus for a robot welding gun having a transformer.
2. Description of Background Art
Hithertofore, a cable for a robot welding gun was known which included a pair of conductors for a welding power source and a pair of conductors for a valve control power source. The cable was utilized for connecting a robot welding gun having a transformer to a robot controller. When this type of cable is continually used in an unmanned factory, it is usual that even after an insulation coating for the cable is damaged, the cable is still continued to be used with its damaged portion remaining unchecked. As a result, a problem may occur when the conductors thereof contact an external object, such as a workpiece, a jig or the like, on the grounding side and an excessive current flows therethrough. The grounding of the cable may cause injury to an individual or a fire or the like.